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Warm or Cold Contrast Medium in the Micturating Cystourethrogram (MCUG): Which is Best?
Clinical Radiology (2003) 58: 551–554 doi:10.1016/S0009-9260(03)00161-2, available online at www.sciencedirect.com
Warm or Cold Contrast Medium in the Micturating Cystourethrogram (MCUG): Which is Best? T. R. GOODMAN, T. KILBORN, R. PEARCE Department of Radiology, John Radcliffe Hospital, Oxford, UK Received: 28 February 2003 Accepted: 13 March 2003 AIM: The purpose of this study was to determine what difference using room temperature (“cold”) or body temperature (“warm”) contrast medium had on the outcome of MCUG examinations in infants under 1 year of age. MATERIALS AND METHODS: One hundred infants (50 males and 50 females) referred for an MCUG were identified. Individuals with known bladder neuropathy were excluded. Each was randomized to receive either warm or cold contrast medium. The screening time, volume of contrast instilled, number of attempts at voiding, patient distress, completeness of bladder emptying and incidence of reflux were measured and the results between the two groups compared. RESULTS: No difference was found between the two groups with regards to screening time, volume of contrast instilled or number of attempts at voiding. There was a statistically significant (p < 0:05; chi square) difference in distress levels, with more children crying during instillation of cold contrast medium than warm. Bladder emptying was more often to completion when using cold contrast medium (32 compared with 16%), and vesicoureteric reflux (VUR) was more commonly demonstrated when using warm contrast medium (16 compared with 6%), although these values did not reach statistical significance. CONCLUSION: Warm contrast medium causes significantly less distress than cold contrast medium, but does not prolong screening time or increase the volume of contrast required. T. R. Goodman et al. (2003). Clinical Radiology 58: 551–554. q 2003 Published by Elsevier Science Ltd on behalf of The Royal College of Radiologists. Key words: infants, voiding cystourethrography, contrast medium.
INTRODUCTION
The micturating cystourethrogram (MCUG) accounts for 40% of all fluoroscopic procedures performed on children in Europe [1]. An MCUG examination is undoubtedly an unpleasant experience for patients, their carers and radiology staff performing the test. The MCUG has been cited as being a more highly distressing investigation than several other invasive procedures performed on children [2]. Unfortunately, it is also an examination for which there are no recognized standard protocols. At our institution, we have made a concerted effort to make the experience as pleasant as possible for patients and carers. As part of this initiative we hypothesized that one of the most significant components of patient discomfort was the filling of the bladder with cold liquid, and its subsequent micturition. As such, in an attempt to make the procedure more comfortable we Guarantor and correspondent: Dr T. R. Goodman, Department of Radiology, John Radcliffe Hospital, Oxford OX3 9DU, UK. Tel: þ441865-220816; Fax: þ 44-1865-220801; E-mail: [email protected]. uk 0009-9260/03/$30.00/0
considered using contrast medium warmed to body temperature. This study was carried out in order to determine whether this would have any effect on patient distress and whether using warm contrast medium would have any adverse effects on MCUG imaging outcomes.
MATERIALS AND METHODS
Infants under the age of 1 year referred for an MCUG examination were identified prospectively. Infants being investigated for ambiguous genitalia, follow-up posterior urethral valve ablation and known neuropathic bladders were excluded. The clinical indications for each group are shown in Table 1. Fifty male infants and 50 female infants were identified and randomized to receive either contrast medium of room temperature (218C, n ¼ 50) or contrast medium warmed in an incubator to 388C ðn ¼ 50Þ: All carers received an information leaflet before the
q 2003 Published by Elsevier Science Ltd on behalf of The Royal College of Radiologists.
552
CLINICAL RADIOLOGY
Table 1 – Indications for MCUG requests by contrast medium temperature
Urinary tract infections Hydronephrosis Multicystic dysplastic kidney Family history of reflux Others Total
Warm
Cold
16 24 2 4 4 50
19 24 2 3 2 50
Table 3 – Comparison of MCUG process, results and distress by contrast medium temperature
Distress (crying) present, percent Volume of contrast, ml (geometric mean) Mean duration, s Median number of voiding attempts Complete emptying, percent Reflux demonstrated, percent p †
procedure and were counselled by a paediatric nurse immediately before entering the fluoroscopy suite. All procedures were performed using the same local MCUG protocol. The fluoroscopy room was warmed to 268C and all catheterizations were performed using an aseptic technique by a radiology nurse or paediatric radiologist. Lignocaine local anaesthetic gel (Instillagel, Clinimed Ltd, High Wycombe, Bucks) was applied to the urethral orifice and a 5 F feeding tube (Bard Ltd, Crawley, West Sussex) was used for all children. After emptying the patient’s bladder via the catheter, Urografin 150 (Schering Ltd, Burgess Hill, West Sussex) was instilled by means of a gravity fed infusion. The height of the contrast medium bottle was 1.9 m in all cases. This was continued until the child voided spontaneously. All fluoroscopy was performed by a paediatric radiologist or a trainee under a paediatric radiologist’s supervision. Gridless pulsed fluoroscopy at 3 pulses/s was used for all examinations and a set protocol of routine exposures was taken. At the conclusion of each examination the following parameters were measured: patient distress, incidence and grade of reflux, number of attempts at voiding until a satisfactory void was obtained, volume of contrast medium required to void, completeness of bladder emptying and screening time. Patient distress was assessed by a paediatric nurse who was blinded to the temperature of contrast medium received. Distress was graded according to a predetermined scale (Table 2). Continuous outcome variables were compared using t-tests for normally distributed data and Wilcoxon rank sum tests for non-normally distributed data. A log transformation was used for volume because the distribution was not close to normal and the shapes of distributions of the untransformed data differed by group. Categorical outcomes were analysed by chi square tests and by Fisher’s exact test where expected numbers in any cell were less than 5.
‡ §
Warm
Cold
p-Value
28 44.1 26.9 1 16 16
52 39.3 28.1 1 32 6
0.014p 0.13† 0.6† 0.53‡ 0.10§ 0.20§
Chi square test. t-Test. Rank sum test. Fisher’s exact test.
RESULTS
One hundred studies were performed in 50 male and 50 female infants. Equal numbers of boys and girls received cold and warm contrast medium. The results are shown in Table 3.
Distress The two groups showed a borderline significant difference in their distress scores (p ¼ 0:051; Fisher’s exact test). Examination of the data indicated that the main difference was in the larger number scoring 0 or 1 in the warm group compared with the cold group where many more infants scored 2 (Fig. 1). Dividing each group into those scoring 1 or less compared with two or more shows that 72% of the warm contrast medium group had no or minimal symptoms compared with 48% of the cold group (p ¼ 0:014; chi square test).
Reflux There was more than twice the amount of reflux in the warm group compared with the cold group although this difference did not reach statistical significance (p ¼ 0:2; Fisher’s exact test). In the warm group there were eight cases of reflux (16%) compared with three (6%) in the cold group. With regards to the grade of reflux, there were two grade I, one grade II, three grade III and three grade V in the warm group. One patient had bilateral grade III and V reflux. In the cold group there were two grade 1 and one grade IV cases of vesicoureteric reflux.
Table 2 – Scale for perceived infant stress during MCUG procedure 0 1 2 3 4
No Distress Flinching during infusion only Mild distress: crying ,50% of examination Moderate distress: crying .50% of examination Severe distress: crying throughout examination
Fig. 1 – The variation in perceived distress using different contrast medium.
WARM OR COLD CONTRAST MEDIUM IN THE MICTURATING CYSTOURETHROGRAM (MCUG): WHICH IS BEST?
Number of Attempts to Void There was no difference in either group with regards to the average number of attempts to satisfactorily void (p ¼ 0:53; rank sum test).
Volume of Contrast Medium Required There was no difference in either group with regards to the average volume of contrast medium required to initiate voiding (p ¼ 0:13; t-test). The average in the warm group was 44.1 ml and in the cold group 39.3 ml.
Completeness of Bladder Emptying There was nearly three times as many complete bladder emptying episodes in the cold group (16 patients) compared with the warm group (six patients). This difference, however, did not reach statistical significance (p ¼ 0:1; Fisher’s exact test).
Screening Time There was no difference in either group with regards to the average screening time (28.1 s in the cold group compared with 26.9 s in the warm group). DISCUSSION
It would seem sensible to make the MCUG examination as physiological as possible in order to reproduce the voiding reflex accurately and to make the experience as comfortable as possible for the child. Using contrast medium at body temperature would seem to be a quick, easy, cheap and practical way to approach this. Another study has assessed the use of warm contrast medium in MCUG examinations [3], but did not analyse patient distress. When we used room temperature contrast medium, our paediatric nurse commented on noticing the infants legs “flinching” once voiding of the cold contrast medium had begun and that distress occurred after this point. We felt that infusing warm contrast medium would be more comfortable for the patient during bladder filling and that this would prevent the presumed uncomfortable feeling of cold liquid against the skin surface during voiding. Because of this, we hypothesized that using warm contrast might lead to a more solitary voiding pattern, rather than the stop/start pattern more usually encountered. We considered using warm contrast medium for all children but were curious as to the disadvantages this might have on reflux detection rates and screening times. Physiological studies have shown that there are cold temperature receptors in the bladder wall and urethra that stimulate unmyelinated C-afferents in the pelvic and pudendal nerves that consequently stimulate detrusor contraction and initiate micturition [4]. This reflex is suppressed by a descending inhibitory signal from higher centres in children over 4 years of age [4]. If the detrusor muscle is stimulated earlier in the MCUG examination using cold
553
contrast medium, then we hypothesized that we would require a smaller volume of contrast to initiate voiding and thus make the examination (and therefore the screening time) shorter. This would have obvious dose reduction advantages to the child who is on average being exposed to an entrance skin dose of 1.9 mGy per examination [5]. Using cold contrast medium would also have the theoretical advantage of facilitating increased efficiency in the fluoroscopy suite due to faster patient throughput. Furthermore, if the detrusor muscle is stimulated earlier and more vigorously by the cold receptors then we also hypothesized that there would be a greater incidence of VUR detection and that bladder emptying would be more complete. If this were the case, the potential advantages gained by using warm contrast medium (less patient distress and less number of attempts at voiding) might be outweighed by the physiological arguments for using cold contrast medium (faster examination with more VUR detection and reduced patient irradiation). Only two of our hypotheses were supported by this study: distress and bladder emptying. The distress observed in infants receiving cold contrast medium was higher than that measured in the warm group. Assessing distress in infants is difficult. Certain children in both groups were upset as soon as they lay on the table, whereas others were calm throughout the MCUG examination. It could be argued that distress is so multifactorial that identifying which area a child finds most stressful is impossible. Most would suggest that the catheterization is the most distressing component of an MCUG examination, although in our experience once fluoroscopy commenced, the majority of infants were calm. We also perceived that infant distress appeared to occur most towards the end of the examination when the bladder is full and voiding has not yet started. Assuming all the environmental variables were equal and that we used a large number of children, we can only argue that the patient personality factor was minimized as much as possible. We considered using salivary cortisol to assess stress during the examination, but it was felt that a further invasive procedure would be difficult to justify. We are convinced that children are more comfortable when warm liquid is infused into the bladder as well as when warm liquid is voided. As we expected, complete bladder emptying was demonstrated more often in the cold group. This is likely to be as a direct result of the increased detrusor activity induced by the cold liquid. We know that infants do not void to completion normally [6] and as such the reduced incidence of this in the warm group should not impact adversely on clinical decision making. We were pleasantly surprised by our other hypotheses being proved wrong. Our worries about the examination screening time taking longer with warm contrast medium were unfounded. In the same way, the volume required to initiate voiding was not greater in the warm group. With the lower distress levels in the warm group, we did anticipate a more solitary voiding pattern, but this was disproved. The higher incidence of reflux in the warm group was an unexpected finding. We can only suggest that the more physiological response by the bladder to being filled with
554
CLINICAL RADIOLOGY
warm contrast medium facilitates vesicoureteric reflux in susceptible children. In summary, this study shows that contrast medium warmed to body temperature causes less distress in infants without any deleterious effects on other parameters associated with this examination. We recommend that warm contrast medium be used for all children undergoing MCUG examinations.
REFERENCES 1 Schneider K, Kruger-Stollfuss I, Ernst G, Kohn MM. Paediatric fluoroscopy—a survey of children’s hospitals in Europe. Pediatr Radiol, 2001;31:238– 246.
2 Stashinko EE, Goldberger J. Test or trauma: the voiding cystourethrogram experience of young children. Issues Comprehensive Pediatr Nurs, 1998;21:85 –96. 3 Zerin JM. Impact of contrast material temperature on bladder capacity and cystographic diagnosis of vesicoureteric reflux in children. Radiology, 1993:161–164. 4 Geirsson G, Lindstrom S, Fall M, et al. Positive bladder cooling test in neurologically normal young children. J Urol, 1993;151:446–448. 5 Baxopoulos EV, Prassopoulos PK, Damilakis JE, et al. A comparison between digital fluoroscopic hard copies and 105 mm spot films in evaluating vesicoureteric reflux in children. Pediatr Radiol, 1998;28: 162–166. 6 Sillen U. Bladder function and development in healthy infants. J Urol, 2001;166:2376–2381.
Warm or Cold Contrast Medium in the Micturating Cystourethrogram (MCUG): Which is Best? T. R. GOODMAN, T. KILBORN, R. PEARCE Department of Radiology, John Radcliffe Hospital, Oxford, UK Received: 28 February 2003 Accepted: 13 March 2003 AIM: The purpose of this study was to determine what difference using room temperature (“cold”) or body temperature (“warm”) contrast medium had on the outcome of MCUG examinations in infants under 1 year of age. MATERIALS AND METHODS: One hundred infants (50 males and 50 females) referred for an MCUG were identified. Individuals with known bladder neuropathy were excluded. Each was randomized to receive either warm or cold contrast medium. The screening time, volume of contrast instilled, number of attempts at voiding, patient distress, completeness of bladder emptying and incidence of reflux were measured and the results between the two groups compared. RESULTS: No difference was found between the two groups with regards to screening time, volume of contrast instilled or number of attempts at voiding. There was a statistically significant (p < 0:05; chi square) difference in distress levels, with more children crying during instillation of cold contrast medium than warm. Bladder emptying was more often to completion when using cold contrast medium (32 compared with 16%), and vesicoureteric reflux (VUR) was more commonly demonstrated when using warm contrast medium (16 compared with 6%), although these values did not reach statistical significance. CONCLUSION: Warm contrast medium causes significantly less distress than cold contrast medium, but does not prolong screening time or increase the volume of contrast required. T. R. Goodman et al. (2003). Clinical Radiology 58: 551–554. q 2003 Published by Elsevier Science Ltd on behalf of The Royal College of Radiologists. Key words: infants, voiding cystourethrography, contrast medium.
INTRODUCTION
The micturating cystourethrogram (MCUG) accounts for 40% of all fluoroscopic procedures performed on children in Europe [1]. An MCUG examination is undoubtedly an unpleasant experience for patients, their carers and radiology staff performing the test. The MCUG has been cited as being a more highly distressing investigation than several other invasive procedures performed on children [2]. Unfortunately, it is also an examination for which there are no recognized standard protocols. At our institution, we have made a concerted effort to make the experience as pleasant as possible for patients and carers. As part of this initiative we hypothesized that one of the most significant components of patient discomfort was the filling of the bladder with cold liquid, and its subsequent micturition. As such, in an attempt to make the procedure more comfortable we Guarantor and correspondent: Dr T. R. Goodman, Department of Radiology, John Radcliffe Hospital, Oxford OX3 9DU, UK. Tel: þ441865-220816; Fax: þ 44-1865-220801; E-mail: [email protected]. uk 0009-9260/03/$30.00/0
considered using contrast medium warmed to body temperature. This study was carried out in order to determine whether this would have any effect on patient distress and whether using warm contrast medium would have any adverse effects on MCUG imaging outcomes.
MATERIALS AND METHODS
Infants under the age of 1 year referred for an MCUG examination were identified prospectively. Infants being investigated for ambiguous genitalia, follow-up posterior urethral valve ablation and known neuropathic bladders were excluded. The clinical indications for each group are shown in Table 1. Fifty male infants and 50 female infants were identified and randomized to receive either contrast medium of room temperature (218C, n ¼ 50) or contrast medium warmed in an incubator to 388C ðn ¼ 50Þ: All carers received an information leaflet before the
q 2003 Published by Elsevier Science Ltd on behalf of The Royal College of Radiologists.
552
CLINICAL RADIOLOGY
Table 1 – Indications for MCUG requests by contrast medium temperature
Urinary tract infections Hydronephrosis Multicystic dysplastic kidney Family history of reflux Others Total
Warm
Cold
16 24 2 4 4 50
19 24 2 3 2 50
Table 3 – Comparison of MCUG process, results and distress by contrast medium temperature
Distress (crying) present, percent Volume of contrast, ml (geometric mean) Mean duration, s Median number of voiding attempts Complete emptying, percent Reflux demonstrated, percent p †
procedure and were counselled by a paediatric nurse immediately before entering the fluoroscopy suite. All procedures were performed using the same local MCUG protocol. The fluoroscopy room was warmed to 268C and all catheterizations were performed using an aseptic technique by a radiology nurse or paediatric radiologist. Lignocaine local anaesthetic gel (Instillagel, Clinimed Ltd, High Wycombe, Bucks) was applied to the urethral orifice and a 5 F feeding tube (Bard Ltd, Crawley, West Sussex) was used for all children. After emptying the patient’s bladder via the catheter, Urografin 150 (Schering Ltd, Burgess Hill, West Sussex) was instilled by means of a gravity fed infusion. The height of the contrast medium bottle was 1.9 m in all cases. This was continued until the child voided spontaneously. All fluoroscopy was performed by a paediatric radiologist or a trainee under a paediatric radiologist’s supervision. Gridless pulsed fluoroscopy at 3 pulses/s was used for all examinations and a set protocol of routine exposures was taken. At the conclusion of each examination the following parameters were measured: patient distress, incidence and grade of reflux, number of attempts at voiding until a satisfactory void was obtained, volume of contrast medium required to void, completeness of bladder emptying and screening time. Patient distress was assessed by a paediatric nurse who was blinded to the temperature of contrast medium received. Distress was graded according to a predetermined scale (Table 2). Continuous outcome variables were compared using t-tests for normally distributed data and Wilcoxon rank sum tests for non-normally distributed data. A log transformation was used for volume because the distribution was not close to normal and the shapes of distributions of the untransformed data differed by group. Categorical outcomes were analysed by chi square tests and by Fisher’s exact test where expected numbers in any cell were less than 5.
‡ §
Warm
Cold
p-Value
28 44.1 26.9 1 16 16
52 39.3 28.1 1 32 6
0.014p 0.13† 0.6† 0.53‡ 0.10§ 0.20§
Chi square test. t-Test. Rank sum test. Fisher’s exact test.
RESULTS
One hundred studies were performed in 50 male and 50 female infants. Equal numbers of boys and girls received cold and warm contrast medium. The results are shown in Table 3.
Distress The two groups showed a borderline significant difference in their distress scores (p ¼ 0:051; Fisher’s exact test). Examination of the data indicated that the main difference was in the larger number scoring 0 or 1 in the warm group compared with the cold group where many more infants scored 2 (Fig. 1). Dividing each group into those scoring 1 or less compared with two or more shows that 72% of the warm contrast medium group had no or minimal symptoms compared with 48% of the cold group (p ¼ 0:014; chi square test).
Reflux There was more than twice the amount of reflux in the warm group compared with the cold group although this difference did not reach statistical significance (p ¼ 0:2; Fisher’s exact test). In the warm group there were eight cases of reflux (16%) compared with three (6%) in the cold group. With regards to the grade of reflux, there were two grade I, one grade II, three grade III and three grade V in the warm group. One patient had bilateral grade III and V reflux. In the cold group there were two grade 1 and one grade IV cases of vesicoureteric reflux.
Table 2 – Scale for perceived infant stress during MCUG procedure 0 1 2 3 4
No Distress Flinching during infusion only Mild distress: crying ,50% of examination Moderate distress: crying .50% of examination Severe distress: crying throughout examination
Fig. 1 – The variation in perceived distress using different contrast medium.
WARM OR COLD CONTRAST MEDIUM IN THE MICTURATING CYSTOURETHROGRAM (MCUG): WHICH IS BEST?
Number of Attempts to Void There was no difference in either group with regards to the average number of attempts to satisfactorily void (p ¼ 0:53; rank sum test).
Volume of Contrast Medium Required There was no difference in either group with regards to the average volume of contrast medium required to initiate voiding (p ¼ 0:13; t-test). The average in the warm group was 44.1 ml and in the cold group 39.3 ml.
Completeness of Bladder Emptying There was nearly three times as many complete bladder emptying episodes in the cold group (16 patients) compared with the warm group (six patients). This difference, however, did not reach statistical significance (p ¼ 0:1; Fisher’s exact test).
Screening Time There was no difference in either group with regards to the average screening time (28.1 s in the cold group compared with 26.9 s in the warm group). DISCUSSION
It would seem sensible to make the MCUG examination as physiological as possible in order to reproduce the voiding reflex accurately and to make the experience as comfortable as possible for the child. Using contrast medium at body temperature would seem to be a quick, easy, cheap and practical way to approach this. Another study has assessed the use of warm contrast medium in MCUG examinations [3], but did not analyse patient distress. When we used room temperature contrast medium, our paediatric nurse commented on noticing the infants legs “flinching” once voiding of the cold contrast medium had begun and that distress occurred after this point. We felt that infusing warm contrast medium would be more comfortable for the patient during bladder filling and that this would prevent the presumed uncomfortable feeling of cold liquid against the skin surface during voiding. Because of this, we hypothesized that using warm contrast might lead to a more solitary voiding pattern, rather than the stop/start pattern more usually encountered. We considered using warm contrast medium for all children but were curious as to the disadvantages this might have on reflux detection rates and screening times. Physiological studies have shown that there are cold temperature receptors in the bladder wall and urethra that stimulate unmyelinated C-afferents in the pelvic and pudendal nerves that consequently stimulate detrusor contraction and initiate micturition [4]. This reflex is suppressed by a descending inhibitory signal from higher centres in children over 4 years of age [4]. If the detrusor muscle is stimulated earlier in the MCUG examination using cold
553
contrast medium, then we hypothesized that we would require a smaller volume of contrast to initiate voiding and thus make the examination (and therefore the screening time) shorter. This would have obvious dose reduction advantages to the child who is on average being exposed to an entrance skin dose of 1.9 mGy per examination [5]. Using cold contrast medium would also have the theoretical advantage of facilitating increased efficiency in the fluoroscopy suite due to faster patient throughput. Furthermore, if the detrusor muscle is stimulated earlier and more vigorously by the cold receptors then we also hypothesized that there would be a greater incidence of VUR detection and that bladder emptying would be more complete. If this were the case, the potential advantages gained by using warm contrast medium (less patient distress and less number of attempts at voiding) might be outweighed by the physiological arguments for using cold contrast medium (faster examination with more VUR detection and reduced patient irradiation). Only two of our hypotheses were supported by this study: distress and bladder emptying. The distress observed in infants receiving cold contrast medium was higher than that measured in the warm group. Assessing distress in infants is difficult. Certain children in both groups were upset as soon as they lay on the table, whereas others were calm throughout the MCUG examination. It could be argued that distress is so multifactorial that identifying which area a child finds most stressful is impossible. Most would suggest that the catheterization is the most distressing component of an MCUG examination, although in our experience once fluoroscopy commenced, the majority of infants were calm. We also perceived that infant distress appeared to occur most towards the end of the examination when the bladder is full and voiding has not yet started. Assuming all the environmental variables were equal and that we used a large number of children, we can only argue that the patient personality factor was minimized as much as possible. We considered using salivary cortisol to assess stress during the examination, but it was felt that a further invasive procedure would be difficult to justify. We are convinced that children are more comfortable when warm liquid is infused into the bladder as well as when warm liquid is voided. As we expected, complete bladder emptying was demonstrated more often in the cold group. This is likely to be as a direct result of the increased detrusor activity induced by the cold liquid. We know that infants do not void to completion normally [6] and as such the reduced incidence of this in the warm group should not impact adversely on clinical decision making. We were pleasantly surprised by our other hypotheses being proved wrong. Our worries about the examination screening time taking longer with warm contrast medium were unfounded. In the same way, the volume required to initiate voiding was not greater in the warm group. With the lower distress levels in the warm group, we did anticipate a more solitary voiding pattern, but this was disproved. The higher incidence of reflux in the warm group was an unexpected finding. We can only suggest that the more physiological response by the bladder to being filled with
554
CLINICAL RADIOLOGY
warm contrast medium facilitates vesicoureteric reflux in susceptible children. In summary, this study shows that contrast medium warmed to body temperature causes less distress in infants without any deleterious effects on other parameters associated with this examination. We recommend that warm contrast medium be used for all children undergoing MCUG examinations.
REFERENCES 1 Schneider K, Kruger-Stollfuss I, Ernst G, Kohn MM. Paediatric fluoroscopy—a survey of children’s hospitals in Europe. Pediatr Radiol, 2001;31:238– 246.
2 Stashinko EE, Goldberger J. Test or trauma: the voiding cystourethrogram experience of young children. Issues Comprehensive Pediatr Nurs, 1998;21:85 –96. 3 Zerin JM. Impact of contrast material temperature on bladder capacity and cystographic diagnosis of vesicoureteric reflux in children. Radiology, 1993:161–164. 4 Geirsson G, Lindstrom S, Fall M, et al. Positive bladder cooling test in neurologically normal young children. J Urol, 1993;151:446–448. 5 Baxopoulos EV, Prassopoulos PK, Damilakis JE, et al. A comparison between digital fluoroscopic hard copies and 105 mm spot films in evaluating vesicoureteric reflux in children. Pediatr Radiol, 1998;28: 162–166. 6 Sillen U. Bladder function and development in healthy infants. J Urol, 2001;166:2376–2381.